Fan



J. H. COHEN March'5, 1940.

FAN

Filed July 26, 1937 2 Sheets-Sheet 1 INVENTOR Josep/v H Cohen B j mama;

March 5, 1940 J. 'H. COHEN 2,192,811

FAN

Filed July 26, 1937 2 Sheets-Sheet 2 Fig. 7

Ill/I45 Fig. /0

INVENTOR I Joseph H Cohen Patented Mar. 5, 1940 UNITED STATES.

PATENT OFFICE FAN Application July 26, 1937; Serial No. 155,673

15 Claims. (Cl. 170-473) The invention relates to fans, and, moreparticularly, to fans for circulating air.

In mamng fans for circulating air, it is essential that the rotatingelements be dynamically it'- balanced so that there will not be anywhipping action .due to the uneven weight distribution when rotated athigh speeds. Dynamic unbalance may be caused by several factors. Onefactor may be the mounting of the blades on the to hub improperly andunsymmetrically with respect to the axis of rotation of the hub. An-.other factor may be the means for mounting the hub upon the drive shaftof the motor.

With respect to the first factor, when blades it made of resilientmaterial, such as rubber are used, dimculty has been found in adequatelysecuring them to the hub so as to withstand the strain due tocentrifugal force when the hub is rapidly rotated. This presents aproblem since the fan blades must be uniformly secured to the hub inprecisely the same manner so that their weight is properly positionedabout the axis of rotation.

accordingly, the present invention provides blades which are adequatelysecured to the hub in such a manner as to be dynamically balanced andwhich are at the same time rigidly secured in place. A

In the preferred form of the invention, the hub t provided with slots ofuniform width into which iierdble rubber blades are inserted from theback or inside oi the hub. The slots adjacenttheir forward end haverecesses on their edgesand the blades are provided with projections ontheir side taces adapted to engage the recesses. This interlockingrelation prevents the blades from slipalong the slots due to therotating action of the fan and pressure oi the air on the blades as theblades are rotated. 0n the inner edge of the blade a plurality ofprojections or lugs are provided and the blade, adjacent each end, isprovided with an ension lying in a plane of the blade. These projectionsand extensions engage the undersuriace of the hub adjacent the edges oithe slot and hold the blade from flying radially Y the clamping elementso that it may be readily tram-the hub due to centrifugal force.

Another feature of the invention resides in the arrangement of theblades on the hub. According tothe present invention, three blades aredd positioned on the hub with their centers spaced 112W, apart. Theblades are of such length that they extend around the hub forapproximately 180. The blades are mounted so as to join the hub in asubstantially helical path with the adjauu cent edges oi the blades inspaced overlapping re1ation.- This arrangement of the blades providesfor an increased blade surface and permits the air drawn by thisincreased blade surface to flow freely through the fan so that more airis given for approximately the same expenditure d of energy, or asmaller motor can be used to obtain the circulation heretofore obtained.

It will be seen, therefore, that with the blades all made of the samematerial and of the same shape and secured symmetrically about the hub Wthat the rotating element will be in dynamic balance.

In another form of the invention the blade is molded so as to have aridge adjacent to but spaced from the edge of the blade which is WWadapted to engage the hub. An insert of metal is molded in the bladealong this edge to reinforce the same. The blade and insert are providedwith holes positioned adjacent the ridge. Pins are provided to beinserted through the holes up so as to engage the inner surface of thehub to prevent the blades from flying out because of centrifugal force.Since the blades are made and secured inidentically the same manner, therotating element will have a proper dynamic balance.

The second factor mentioned above for causing dynamic unbalance of therotary elements resides in the manner in which the hub is secured to theshaft of the motor. If, for example, a so set screw is used, it isdifiicult to get to for adjustment since a hole must be provided in thehub throughwhich an instrument can be inserted to turn the screw. Boththe screw and hole in the hub will alter the weight of the hub so thatsome as provision must be made to counterbalance the same.

According to the present invention, the securing means is positioned inthe hub so as to extend longitudinally of the hub along its axis ofrotano tion. In this manner, unbalance of the hub is avoided and thenecessity of counterbalancing is removed.

Another feature ofthe present invention resides in the mounting of theadjusting means for 45 Other features and advantages will be apparentfrom the specification taken in connection with the drawings, in which:

Figure 1 is a front elevation.

Fig. 2 is a side elevation.

Fig. 3 is a rear view showing the hub and blades.

- Fig. 4 is a side elevation of the hub.

Fig. 5 is a front view of the hub showing the arrangement of the slots.

Fig. 6 is a detailed section of the clamping means.

Fig. 7 is a sectional view of taken along line 'I'I of Fig. 1. t

Fig. 8 is a plan view of one of the blades.

' Fig. 9 is a section of the blade taken along line 9-9 of Fig. 8.

Fig. 10 is a section of the blade taken along line Iii-l0 of. Fig. 8.

Fig. 11 is a plan view of another form of blade,

Fig. 1215 a section of the blade shown in Fig. 11 with it in position onthe hub.

' According to the present invention, a fan motor has secured to itsbottom surface a plate 2| having a socket therein. The plate 2i may besecured to the motor housing in any desired manner, preferablybywelding. Mounted to pivot on the plate is a clamping member 22 adaptedto extend into cooperative relation with the socket in the platetoreceive a supporting member 23 which is herein shown as having a ballfitting in the socket whereby the motor may be universally adjusted. =Ascrew 24 is threaded into the plate and extends through the clampingmember to lock the motor in adjusted position.

hub and blades,

This motor mounting is specifically described and claimed in mydivisional application .Serial No. 276,059, filed May 27, 1939.

A hollow cup-shaped hub is mounted at the forward end of the motor, and,as shown in Fig.

2, is shaped to slightly overlap the forward edge of the motor housingand tapers into a nose at the ,front of the fan. Dlmculty has beenexperienced in mounting such hollow hubs on the drive shaft of the motorso as not to destroy the dynamic balance of the rotating element.Accordingly, the hub is provided with an inwardly-extending sleeve 32,extending axially of the hub and concentric with the axis of rotation ofthe hub. This sleeve may be formed integrally with the hub or may beseparately made and secured thereto. The sleeve has acamming surface 33formed in its bore. Mounted to slide in the bore of the sleeve 32 is aclamping sleeve 34 having a bore of sumcient size to receive a. motorshaft 3i. The end of the sleeve, adapted to receive the motor shaft, issplit so asto form a plurality of clamping elements 35. These clampingelements have camming surfaces 36 thereon, adapted to engage andcooperate with the carnming surface 93 within the sleeve when movedrelatively there- 4 force when the blade is set in motion. vided with awall having thgeads 91 therein which to. The other end of the clampingsleeve is proare adapted to cooperate with a bolt 39 mounted in a recess39 at the nose of the hub so as to lie below the surface of the hub. Thebolt extends along the axis of the hub and upon being rotated slides theclamping sleeve relative to the sleeve 92 whereby thecamming surfacewill move the clamping elements into clamping relation with the end ofthe motor shaft. Since all the elements are symmetrically positionedwith respect 1 to the axis of rotation of the hub, the hub will alwaysbe dynamically. balanced.

A further feature of the invention resides in the accessibility of thebolt 39 whereby the hub may be clamped to the motor shaft. In'priorpractice it has been customary to provide the hub with a sleeve similarto the present sleeve 32 and have a set screw therein adapted to bemoved into engagement with the motor shaft. The hollow hub had to beprovided with an aperture through which a tool could be extended toengage and adjust the set screw. Aside from destroying the balance ofthe hub, the set screw was very difllcult to reach when it was desiredto attach or remove the hub from the shaft. According to the presentinvention, however, the head of the bolt is open to view and easy accesssince it is positioned adjacent the outer surface of the hub and may bereadily operated to lock the hub to the shaft or remove the sametherefrom.

This novel mounting for the hub is described and claimed in mydivisional application Serial fan blades of the fan. The fan blades ofthe present invention, only one of each form being described, are madeof resilient material, preferably rubber, and are tapered incross-section as shown in Figs. 9, 10 and 12.

.In the preferred form of the invention, a blade 42 is made of flexiblerubber and is adapted to be inserted from the inside of the hub.Adjacent its forward end or that end nearest the nose of the hub, theblade has a projection 43 extending from each face of the blade toengage the recesses 4| in the slot to hold the blade from sliding in theslot due to the pressure of the air on the blade when in operation. Thiseffectively prevents shifting of the blade and thereby the weightdistribution of the blade about the axis when such flexibility is notrequired. At each and of the engaging edge of the blade, a projection orwing 45 is formed in the plane of the blade and extends to engage theinner surface of the wall to further prevent the blade from being thrownoutwardly through the slot by centrifugal Three such blades are used,and, according to the present invention, have their centers spaced aboutthe hub at 120 apart. The blades extend around the hub for approximately180 and have their adjacent edges in spaced overlapping relation. Byusing threei blades and positioning them in the manner shown in thedrawings, a greater circulation of air is produced than heretoforeobtained with approximately the same e penditures of energy. The bladesare sufllciently separated to permit the air to freely flow through thefan and have suflicient surface to bite into and draw through a largeamount .of air without undue resistance.

molded so as to have an outwardly-extending ridge 50 adjacent to butspaced from the edge engaging the hub. In the form disclosed, a metalinsert it is molded in the blade in the hub-engaging section toreinforce the blade, although this is not essential as the blade isstiff enough,

and a plurality of holes 52 are drilled or punched through theplate andblade adjacent the ridge. The blade is mounted in the slot from theoutside so that the ridge engages the outer surface of the hub.. A pin53 is inserted through each of the holes and is adapted to engage theinner surface of the hub to hold the blade in position. Preferably, theblade is pressed inwardly through the slot to slightly compress theresilient ridges and the holes in the blades are designed so that thepin may be readily inserted when the blades are held in such position.After the pins have been inserted, the blades are released and theresiliency of the blade forces the blades outwardly through the' slotwhich will pull the pins into firm engagement with the inner surface ofthe hub and securely hold the pins therein against movement. I

Variations and modifications may be made within the scope of thisinvention and portions of the improvements may be used without others.

I claim:

1. In an electric fan, a hub provided with a plurality ofblade-receiving slots of uniform width, the edges of the slots adjacentthe forward end of the same being provided with recesses; blades mountedin the slots having projections adjacent their forward edges adapted toengage the recesses in the ,slot whereby the blade is prevented fromsliding in the slot when in operation;'and means for holding the bladeson the hub.

2. In an electric fan, a hub provided with blade-receiving slots; bladesof flexible material mounted in the slots; means for locking the bladesto the hub without affecting the flexibility of the same comprising aplurality of independent projections extending around the edge of theblade and adapted to engage the inside surface of the hub to hold theblade thereon.

3. In an electric fan, a hub provided with blade-receivingslots; bladesof resilient rubberlike material mounted in the slots; means for lockingthe blades to the hub without impairing the resiliency of said bladescomprising a plurality of pin-like projections extending transversely ofthe blade around the edge of the blade and adapted to engage the ins desurface of the hub to hold the blade' thereon.

4. In an electric fan. a hub provided with blade-receiving slots ofpredetermined fixed length; blades mounted in the slots; means forlooking the blades to the hub, said means including a projection at eachend of the blade extending in the plane of the same, the distancebetween the free ends of said projections being greater than the fixedlength of the slots so that said projections when the blades are mountedin said slots engage the underside surface of the hub adjacent each endof the slot to hold the blade thereon.

5. In an electric fan, a hub provided with blade-receiving slots; bladesmounted in the slots and having a ridge molded thereon adjacent to butspaced from the edge thereof and adapted to engage the hub; a metalinsert molded inthedrawing the separable means into firni fengagemetalinsert; and pins adapted to be inserted through the holes, when theblades are in assembled relation to engage the inner surface of I thehub to hold the blades to the hub.

6. In an electric fan, a hub provided with blade-receiving slots; bladeso'f'resilientmaterial mounted in the slots and having a ridge moldedadjacent to but spaced .from the edge thereof and adapted to engage theouter surface of the hub; a metal insert molded in the blade; the bladehaving holes positioned adjacent the ridge and extending through theblade and metal insert; and pins adapted to be inserted through theholes when the bladesare in assembled relation to engage the innersurface of the hub, the resiliency of the blades holding the pins infirm engagement with the hub.

7. In an electric fan, a hub provided with blade-receiving slots;flexible rubber-like blades mounted in the slots and havinga ridgemolded thereon adjacent to but spaced from the edge thereof and adaptedto engage the outer surface 8. In an electric fan, a hub provided with30 blade-receiving slots; flexible rubber-like blades mounted in theslots and having a continuous ridge molded thereonadjacent to but spacedfrom the edge thereof and adapted to engage the outer surface of thehub; and separable means adapted to bemounted along the edge of theblade in contact with the inner surface of the hub to lock the blade tothe hub.

9. In an electric fan, a hub having slots extending helicallytherealong; flexible rubber blades mounted in said slots; and flexiblemeans for securing said blades in said slots without affecting theflexibility of said blades comprising a plurality of projections spacedalong a thinedge of the blade.

10. In an electric fan, a hollow hub having blade-receiving slotstherein; blades of flexible rubber-like material mounted in said slots,the edge of the blades engaging the hub being relatively thin, wherebythe blade is very flexible and can be readily inserted in the slots fromwithin the hub; and means adjacent said edge extending perpendicularlyto the face of the blade at spaced intervals therealong for engaging thehub to lock the blade in the slot without impairing the flexibility ofthe blades. v

11.- In' an electric fan, a hub having bladereceiving slots therein;blades of flexible rubber like material mounted in said slots, theblades the slots and having a continuous ridge molded thereon adjacentto but spaced from the edge thereof and adapted to engage the outersurface of the hub; and means adapted to be mounted along the edge ofthe blade in contact with the inner surface of the hub to lock thebladeto the slot, the resiliency of the rubber blade ment with the innersurface of the'hub- 14. In an electric fan, a hub provided with.

blade-receiving slots; blades of resilient flexible material mountedinsaid slots to project from the outer surface of the hub; and means forholding the blades in the slots without affecting the flexibility'of thesame, including a plurality of pin-like projections extendingtransversely of the blade, said projections being disposed along atleast a portion of the edged the blade to engage the inner surface ofthe hub to hold the blade thereon.

15. In an electric fan, a hub provided with blade-receiving slots;blades of resilient flexible rubber-like material having a ridge formedthereon and providing an abutment for engaging the outer surface of thehub; and means for holding the blades in the slot without affectin theflexibility of the same, including a plurality of pin-like elementsextending transversely of the blades and disposed along at least aportion of the edge for engaging the inner surface of the hub to holdthe blade thereon.

JOSEPH H. COHEN.

